BIO 311D 2nd Edition Lecture 40Outline of Last Lecture I. Energy flow and trophic structure (How does this affect human k?)II. Nutrient cycling and eutrophicationIII. In class exercise and course instructor surveyOutline of Current Lecture I. Effects of human activity on ecosystemsII. Conservation biology effortsIII. Index Card Questions Current LectureI. Effects of human activity on ecosystemsA. Carbon Cyclea. Producers use CO2 during photosynthesis, producing organic compounds. b. All organisms release CO2 in cellular respirationc. Two ways we’re affecting the cycle: burning fossil fuels, deforestation B. Nitrogen Cyclea. Nitrogen fixation!b. What are some humans are messing with the nitrogen cycle? Pollution, a lot of bare dirt, alters water availability – increase surface runoff, add fertilizer–less likely to runoffc. More fertilizer and fixed nitrogen leads to more runoff C. Eutrophication a. Over production of the organism. Crystal clear lake murky green lake b. Dead zone: dangerously low dissolved oxygen, everyone is going over their K1. Around the Gulf of Mexico many dead zones (fish can’t live here) Runoff from the center of the entire U.S., from the Mississippi river D. Biodiversitya. Habitat loss or habitat degradation1. Habitat destruction and habitat fragmentation: isolated patches support less biodiversity 2. Large patch: the edge effect, the inner area is not influenced by edge effects 3. Smaller patch: the width of the edges is relatively constant, as the total area becomes smaller, the edge becomes proportionately larger 4. Could lessen the edge effects by attaching habitats, “corridors” b. Spread of invasive species1. Introduced species: no natural enemies and parasites so out-compete native species 2. Imported parasites from initial habitat, reintroduce natural parasites c. Over-harvesting and over exploitation 1. How are humans directly affecting populations of fish, shrimp and elephants?Over-fishing fish, shrimp new fishing regulations Elephants, taking the tusks to sell as ivory 2. Indirect effects of over-fishing, over- harvesting: why are killer whales eating more sea otters now?We’re devastating the fish population that feeds the whale population, sothey are now feeding on sea otters E. Fire ecology in Yellowstone National Park and in Bastrop, Texas: How does humanactivity affect this?a. Leading to huge natural disastrous fires, when we try to mess around with natural processesF. Global Amphibian Declinea. Global climate changeII. Conversation Biology EffectsA. How should we define biodiversity for conservation purposes?a. Genetic variationb. Species diversityc. Ecosystem diversityB. What are “ecosystem services”?a. Provide freshwaterb. Reducing air pollution C. Reducing population genetics to ecologya. What are some normal sources of genetic variability in sexually reproducing organisms: independent assortment, crossing overb. How can random evens such as genetic bottlenecking affect genetic variability? – It lessens itD. Relating ecology to genetics and evolution:a. Modern agricultural practices tend to favor monocultures with low genetic varianceb. What happens when a parasite enters?E. Loss of genetic variability and small population size interact to contribute to extinction F. Species- level legislation (Federal)a. World Wildlife Fun World Wide Fund for Nature: world’s largest conservation non-governmental organization (NGO), by membership initially focused on endangered species, but mission has expanded G. Ecosystem (or Ecosystem Based Management)H. Land use and conservation in Costa Ricaa. Attention to biodiversity hot spots, habitat corridorsb. Effects of: ecotourism, carbon credits, agricultural practices, community
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